1. Field of the Invention
The present invention relates to an application operation evaluating apparatus and an application operation evaluating method.
2. Description of the Related Art
Sun protection cosmetics are known as functional cosmetics specified to protect against ultraviolet light. Generally, for evaluation of ultraviolet light protecting effects, numerical index, typically a Sun Protection Factor value (SPF), is used, and consumers buy a product indicated with an appropriate value in accordance with the conditions of actual, use.
The SPF value is a value based on an “ISO in vivo SPF measuring method” (see non-Patent Document 1, for example) or the like and is obtained by an in vivo measuring method using skin of a human test subject. In the in vivo SPF measurement, the measurement is conducted under a condition that a professional engineer (applier) applies a predetermined amount of sun protection cosmetic on the skin by using his/her “finger”. The reason that the applier uses his/her finger in the measurement is to approximate the applied condition on the skin as the consumers mainly use their fingers when actually using the sun protection cosmetic.
However, even when the same sample is applied, if certain repeatability cannot be obtained for the applied conditions, the same measurement result cannot he obtained. Thus, it is required for the professional engineer to actualize the applied conditions with certain repeatability. Further, even when a specific applier (professional engineer) can give high repeatability to the same sample, other appliers may not be able to give the same repeatability. Thus, in order to increase reliability of the measurement results for the in vivo SPF measurement, it is required to increase the repeatability of the applied conditions not only for a certain applier but for multiple appliers.
Here, “to increase the repeatability of the applied conditions” means to actualize the same predetermined applied condition every time. This means that the thickness of the sample on an applied surface is uniform at every time, and the same measurement result is obtained at any position on the applied surface. The actual thickness of the applied sample depends on the ratio remained in the ingredient. For example, the thickness becomes an order of micron based on the sample applied amount (2.00 mg/cm2) defined by the in vivo SPF measurement method, and it is not easy to apply the sample of this thickness to be uniform on the applied surface by a finger.
Further, recently, an in vitro SPF measurement has been provided (see Patent Documents 2 and 3 and non-Patent Document 3, for example) by which an SPF value of the sample is predicted by a physical measurement using an application substrate that is a substitute for skin (see Patent Document 1 and non-Patent Document 2, for example), without using skin of a test subject. This method is often used at a development stage as this measurement can be easily conducted within a short time with a lower cost.
However, the in vitro SPF measurement is a method for predicting a result of the in vivo SPF measurement, and a sample is applied using a “finger” following the in vivo SPF measurement when applying the sample on the above described application substrate. Thus, at the in vitro SPF measurement and at the in vivo SPF measurement, the above described repeatability of the applied conditions is required. Recently, improvement of the repeatability has been provided by standardizing details of the application method (see Patent Document 4, for example).